Osteitis deformans is a chronic bone disorder more commonly known as Paget’s disease of bone. This condition involves abnormal bone renewal and repair. It can lead to bones becoming enlarged, weak, and misshapen over time.
Understanding Paget’s Disease of Bone
Paget’s disease of bone is characterized by a disruption in the body’s natural bone remodeling process. Normally, bone is continuously broken down by cells called osteoclasts and then rebuilt by cells called osteoblasts, maintaining a balanced and strong skeleton. In individuals with Paget’s disease, osteoclasts become excessively active, leading to an accelerated breakdown of old bone tissue. This rapid resorption is then followed by an overactive response from osteoblasts, which produce new bone at an unusually fast rate.
The newly formed bone in Paget’s disease is often disorganized, structurally abnormal, and weaker than healthy bone. This chaotic formation can result in bones that are enlarged, fragile, and prone to deformities. While any bone can be affected, the disease most frequently impacts the pelvis, skull, spine, and the long bones of the legs like the femur and tibia. The disease usually affects one or several bones, but it does not spread from one bone to another.
Recognizing the Signs and Symptoms
Many individuals with Paget’s disease of bone experience no symptoms at all, with the condition often discovered incidentally during X-rays or blood tests for other reasons. When symptoms do occur, bone pain is the most frequent complaint, often described as a deep, aching sensation that can worsen at night. This pain may localize to areas near joints affected by the disease.
Bone deformities are also common, manifesting as bowed legs, an enlarged skull, or a curved spine. If the skull is affected, an overgrowth of bone can lead to headaches or hearing loss. Nerve compression can occur if the spine or skull bones enlarge, causing pain, tingling, numbness, or weakness in the limbs. In some cases, the skin over affected bones may feel warm due to increased blood flow.
Exploring Causes and Risk Factors
The exact cause of Paget’s disease of bone remains unclear, though it is believed to stem from a combination of genetic and environmental influences. Genetic factors play a significant role, with mutations in the Sequestosome 1 (SQSTM1) gene being the most commonly identified genetic link. These mutations are found in many individuals, particularly those with a family history of the disease.
Environmental factors are also thought to contribute, evidenced by a decline in the frequency and severity of the disease in many regions over recent decades. While no definitive environmental trigger has been identified, theories include exposure to certain viruses or dietary deficiencies. Age is a strong risk factor, with the disease being more common in people over 50 years old. Geographical prevalence shows higher rates in countries like the United Kingdom, Australia, New Zealand, and North America, particularly in populations of European descent.
Diagnosis and Treatment Approaches
Diagnosing Paget’s disease of bone typically involves a combination of medical assessments. Blood tests often reveal elevated levels of alkaline phosphatase (ALP), an enzyme that indicates increased bone turnover. X-rays are also used, as they can show characteristic bone changes such as enlargement, deformities, and areas of abnormal bone breakdown and formation. A bone scan, which involves injecting a small amount of radioactive material, can identify all affected areas of the skeleton by highlighting regions of increased bone activity. Occasionally, a bone biopsy may be performed to confirm the diagnosis or rule out other conditions.
Treatment focuses on managing symptoms, preventing complications, and normalizing the abnormal bone metabolism. Bisphosphonates are the most common medication used, working by inhibiting the excessive bone breakdown by osteoclasts. Zoledronic acid, often given as a single intravenous infusion, is a potent bisphosphonate that can normalize bone remodeling for several years. Oral bisphosphonates like risedronate are also used.
Pain relief strategies may include over-the-counter medications. In cases of severe complications such as fractures, joint damage leading to arthritis, or nerve compression, surgery may be considered to realign bones, replace joints, or relieve pressure on nerves.